The Asian Summer pattern is a prominent mode from June-August. The pattern is monopole in nature, with anomalies of the same sign observed throughout southern Asia and northeastern Africa. A positive phase of the pattern is indicated by above-normal heights throughout southern Asia and northeastern Africa. The Asian Summer ... pattern exhibits considerable interannual and interdecadal variability, with a pattern of one sign observed for several consecutive years, followed by a pattern of the opposite sign for several consecutive years. For example, a positive phase of the pattern dominated the summertime circulation from 1987-1990. This period was preceded by a three-year period (1984-1987) in which the negative phase of the pattern was prominent.